Commit b6958ce4 authored by Eddie Dong's avatar Eddie Dong Committed by Avi Kivity
Browse files

KVM: Emulate hlt in the kernel 



By sleeping in the kernel when hlt is executed, we simplify the in-kernel
guest interrupt path considerably.

Signed-off-by: default avatarGregory Haskins <ghaskins@novell.com>
Signed-off-by: default avatarYaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 1fd4f2a5

drivers/kvm/i8259.c

+3 −0
Original line number Diff line number Diff line
@@ -413,8 +413,11 @@ static void picdev_read(struct kvm_io_device *this, 
static void pic_irq_request(void *opaque, int level)

{

	struct kvm *kvm = opaque;

	struct kvm_vcpu *vcpu = kvm->vcpus[0];



	pic_irqchip(kvm)->output = level;

	if (vcpu)

		kvm_vcpu_kick(vcpu);

}



struct kvm_pic *kvm_create_pic(struct kvm *kvm)

drivers/kvm/irq.c

+4 −0
Original line number Diff line number Diff line
@@ -70,6 +70,10 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu) 
{

	int ipi_pcpu = vcpu->cpu;



	if (waitqueue_active(&vcpu->wq)) {

		wake_up_interruptible(&vcpu->wq);

		++vcpu->stat.halt_wakeup;

	}

	if (vcpu->guest_mode)

		smp_call_function_single(ipi_pcpu, vcpu_kick_intr, vcpu, 0, 0);

}

drivers/kvm/kvm.h

+2 −0
Original line number Diff line number Diff line
@@ -231,6 +231,7 @@ struct kvm_stat { 
	u32 signal_exits;

	u32 irq_window_exits;

	u32 halt_exits;

	u32 halt_wakeup;

	u32 request_irq_exits;

	u32 irq_exits;

	u32 light_exits;
@@ -353,6 +354,7 @@ struct kvm_vcpu { 
	gva_t mmio_fault_cr2;

	struct kvm_pio_request pio;

	void *pio_data;

	wait_queue_head_t wq;



	int sigset_active;

	sigset_t sigset;

drivers/kvm/kvm_main.c

+35 −6
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ static struct kvm_stats_debugfs_item { 
	{ "signal_exits", STAT_OFFSET(signal_exits) },

	{ "irq_window", STAT_OFFSET(irq_window_exits) },

	{ "halt_exits", STAT_OFFSET(halt_exits) },

	{ "halt_wakeup", STAT_OFFSET(halt_wakeup) },

	{ "request_irq", STAT_OFFSET(request_irq_exits) },

	{ "irq_exits", STAT_OFFSET(irq_exits) },

	{ "light_exits", STAT_OFFSET(light_exits) },
@@ -248,6 +249,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id) 
	vcpu->mmu.root_hpa = INVALID_PAGE;

	vcpu->kvm = kvm;

	vcpu->vcpu_id = id;

	init_waitqueue_head(&vcpu->wq);



	page = alloc_page(GFP_KERNEL | __GFP_ZERO);

	if (!page) {
@@ -1307,16 +1309,42 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
}

EXPORT_SYMBOL_GPL(emulate_instruction);



/*

 * The vCPU has executed a HLT instruction with in-kernel mode enabled.

 */

static void kvm_vcpu_kernel_halt(struct kvm_vcpu *vcpu)

{

	DECLARE_WAITQUEUE(wait, current);



	add_wait_queue(&vcpu->wq, &wait);



	/*

	 * We will block until either an interrupt or a signal wakes us up

	 */

	while(!(irqchip_in_kernel(vcpu->kvm) && kvm_cpu_has_interrupt(vcpu))

	      && !vcpu->irq_summary

	      && !signal_pending(current)) {

		set_current_state(TASK_INTERRUPTIBLE);

		vcpu_put(vcpu);

		schedule();

		vcpu_load(vcpu);

	}



	remove_wait_queue(&vcpu->wq, &wait);

	set_current_state(TASK_RUNNING);

}



int kvm_emulate_halt(struct kvm_vcpu *vcpu)

{

	if (vcpu->irq_summary ||

		(irqchip_in_kernel(vcpu->kvm) && kvm_cpu_has_interrupt(vcpu)))

	++vcpu->stat.halt_exits;

	if (irqchip_in_kernel(vcpu->kvm)) {

		kvm_vcpu_kernel_halt(vcpu);

		return 1;



	} else {

		vcpu->run->exit_reason = KVM_EXIT_HLT;

	++vcpu->stat.halt_exits;

		return 0;

	}

}

EXPORT_SYMBOL_GPL(kvm_emulate_halt);



int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run)
@@ -2916,6 +2944,7 @@ static long kvm_dev_ioctl(struct file *filp, 


		switch (ext) {

		case KVM_CAP_IRQCHIP:

		case KVM_CAP_HLT:

			r = 1;

			break;

		default:

drivers/kvm/svm.c

+6 −3
Original line number Diff line number Diff line
@@ -1398,8 +1398,11 @@ static void do_interrupt_requests(struct vcpu_svm *svm, 
static void post_kvm_run_save(struct vcpu_svm *svm,

			      struct kvm_run *kvm_run)

{

	kvm_run->ready_for_interrupt_injection

		= (svm->vcpu.interrupt_window_open &&

	if (irqchip_in_kernel(svm->vcpu.kvm))

		kvm_run->ready_for_interrupt_injection = 1;

	else

		kvm_run->ready_for_interrupt_injection =

					 (svm->vcpu.interrupt_window_open &&

					  svm->vcpu.irq_summary == 0);

	kvm_run->if_flag = (svm->vmcb->save.rflags & X86_EFLAGS_IF) != 0;

	kvm_run->cr8 = get_cr8(&svm->vcpu);